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Articles 1 - 7 of 7
Full-Text Articles in Pathogenic Microbiology
Evaluation Of The Virulence Potential Of Avian Pathogenic Escherichia Coli Isolated From Broiler Breeders With Colibacillosis In Mississippi, Jiddu Joseph
Theses and Dissertations
Avian pathogenic Escherichia coli (APEC) is a bacterium that is responsible for colibacillosis in birds. However, information about broiler breeder APEC isolates is limited, but the data is critical due to the transfer of this bacteria down the production pyramid to progenies resulting in high mortality. Therefore, we evaluated the phenotypic virulence characteristics of 28 isolates using embryo lethality and day-old chick challenge assays. Also, the in vitro adhesion and invasion potential of selected nine isolates were identified. Results showed more than 1/3rd of the isolates were highly virulent and the virulence increased as the number of virulence-associated genes …
The Type Iv Pilus Secretin Bfpb: Structural Analysis And Binding Interactions, Janay I. Little
The Type Iv Pilus Secretin Bfpb: Structural Analysis And Binding Interactions, Janay I. Little
Theses and Dissertations
Enteropathogenic Escherichia coli (EPEC) causes severe diarrhea in young children. The type IV pilus (T4P) of EPEC, known as the bundle-forming pilus (BFP), plays an important role in EPEC pathogenesis. T4Ps are a family of surface appendages that are important for adhesion, colonization, biofilm formation, virulence, twitching motility and many other functions. One essential component of the BFP system is the secretin, BfpB. Secretins are a large family of integral outer membrane proteins found in T4Ps as well as type II and type III secretion systems, and filamentous phages. Details of the secretin structure have been limited to the overall …
The Role Of Manganese In Streptococcus Sanguinis, Tanya M. Puccio
The Role Of Manganese In Streptococcus Sanguinis, Tanya M. Puccio
Theses and Dissertations
Streptococcus sanguinis is primarily associated with oral health as a commensal bacterium. As an opportunistic pathogen, S. sanguinis is capable of colonizing heart valve vegetations, leading to the disease infective endocarditis. Previous studies from our lab have identified the high-affinity manganese transporter SsaACB as important for endocarditis virulence. The impact that manganese depletion has on S. sanguinis had never been evaluated and a secondary manganese transporter has not been identified. Thus, we employed the use of a fermentor to control large-scale growth over time and depleted manganese in an ΔssaACB mutant using a metal chelator, EDTA. The changes in …
Orientia Tsutsugamushi Modulates Endoplasmic Reticulum Stress To Benefit Its Intracellular Growth And Targets Nlrc5 To Inhibit Major Histocompatibility Complex I Expression, Kyle G. Rodino
Theses and Dissertations
Scrub typhus, caused by the obligate intracellular bacterium Orientia tsutsugamushi, afflicts one million people annually. Despite being a global health threat, little is known about O. tsutsugamushi pathogenesis. Here, we demonstrate that O. tsutsugamushi modulates the ER and ER-associated processes as mechanisms of nutritional virulence and immune evasion. To obtain amino acids to fuel replication, O. tsutsugamushi simultaneously induces ER stress and the unfolded protein response (UPR) while inhibiting ER-associated degradation (ERAD) during early infection time points. During exponential growth, the bacterium releases the ER bottleneck, resulting in generation of ERAD-derived amino acids that it parasitized for replication. …
Acid Sphingomyelinase Is Essential For Vacuolar Development Of A. Phagocytophilum., Chelsea Cockburn
Acid Sphingomyelinase Is Essential For Vacuolar Development Of A. Phagocytophilum., Chelsea Cockburn
Theses and Dissertations
Obligate intracellular bacteria are significant causes of morbidity and mortality with over two hundred and fifty million infections worldwide annually. One such bacterium, Anaplasma phagocytophilum is the etiologic agent of human granulocytic anaplasmosis (HGA), a tick-transmitted febrile illness. Previous studies have shown that A. phagocytophilum lacks genes for cholesterol biosynthesis and solely relies on Niemann Pick protein type C (NPC)1-mediated low density lipoprotein (LDL)-derived cholesterol to complete its infection cycle.Acid sphingomyelinase (ASMase) is a lysosomal enzyme that is essential for diverse cellular processes including liberation of LDL-derived cholesterol from the lysosome. By first studying A. phagocytophilum, we found that …
Contribution Of A Class Ii Ribonucleotide Reductase To The Manganese Dependence Of Streptococcus Sanguinis, John L. Smith
Contribution Of A Class Ii Ribonucleotide Reductase To The Manganese Dependence Of Streptococcus Sanguinis, John L. Smith
Theses and Dissertations
Manganese-deficient Streptococcus sanguinis mutants exhibit a dramatic decrease in virulence for infective endocarditis and in aerobic growth in manganese-limited media. Loss of activity of a manganese-dependent, oxygen-dependent ribonucleotide reductase (RNR) could explain the decrease in virulence. When the genes encoding this RNR are deleted, there is no growth of the mutant in aerobic broth culture or in an animal model. Testing the contribution of the aerobic RNR to the phenotype of a manganese transporter mutant, a heterologous class II RNR from Lactobacillus leichmannii called NrdJ that requires B12 rather than manganese as a cofactor was previously introduced into an …
The Characterization Of A Putative Virulence Factor Expressed By Sneathia Amnii, Amy Sanford
The Characterization Of A Putative Virulence Factor Expressed By Sneathia Amnii, Amy Sanford
Theses and Dissertations
Preterm birth, defined at birth before 37 weeks gestation, affects millions of newborns worldwide every year. Preterm birth is a leading cause of infant morbidity and mortality. One major cause of preterm birth is preterm premature rupture of membranes (PPROM), which can be triggered by bacterial infection and inflammation. A bacterial species that has been implicated in preterm birth and other obstetric complications is Sneathia amnii. The goals of this study were to observe cytopathogenic effects caused by S. amnii strain Sn35 and identify putative virulence factors causing those effects. Sn35 was able to adhere to, invade, and damage/kill …